In recent years, snowmobiles, particularly high performance snowmobiles, have been provided with fuel injection systems. Typically, the fuel injection systems are electronic in nature and similar to the electronic fuel injection systems that are common in four-cycle engines. The electronic control unit (ECU) of the fuel injection system employs a collection of sensors to measure a variety of parameters relating to engine condition and operation such as engine speed, throttle position, engine temperature and barometric pressure. By monitoring these (and other) engine parameters, the ECU is capable of directing the fuel injection system to deliver the amount of fuel and air mixture necessary for the desired performance characteristics of the engine.
To operate a snowmobile, the rider will turn the ignition switch to the "run" position, typically through the use of a key, to engage the ignition system. The ignition switch can also be turned to the "off" position, thereby incapacitating the ignition system and stopping the engine. Snowmobiles, however, also typically include an emergency stop or kill switch that, when activated by the rider, will interrupt the ignition system, thereby causing the engine to stop.
Although primarily designed for emergency uses, riders will frequently use the emergency stop switch as a means of regularly stopping their snowmobiles. Snowmobile riders thus are also in the habit of leaving the ignition switch in the "run" position when the machine is stopped, and some also return the emergency stop switch to the "run" position after using it to stop the machine. Stopping a snowmobile via the emergency stop switch, however, does not necessarily disengage the ECU from the battery if the ECU is powered from the contacts on the ignition stop switches. Thus, the ECU may continue to draw power from the battery after the engine has been shut down. If the snowmobile is left for an extended period of time with the ignition switch in the "run" position, there is a possibility of the battery being drained to a point where there will be insufficient power to reactivate the electrical components of the snowmobile and the rider will then be stranded.
Prior art solutions to the problem of battery drainage have involved supplying the electrical components of the engine with a momentary pulse of power when the rider activates a switch. In such systems, the power is maintained after the switch activation through the use of a relay or solid state switch so that the ECU can shut itself off once it detects that the engine has been inactive for set period of time. An example of such a system is U.S. Pat. No. 5,024,205 by W. Gatza and R. Chasteen.
The prior art solutions, however, suffer from significant disadvantages. One disadvantage is that positioning the ignition and emergency stop switches in their "run" positions will not necessarily result in the machine being ready for starting. This is counter to the expectations of most snowmobile riders and thus can become a nuisance or a source of confusion to the snowmobile operator. In some variations, the rider must turn the ignition switch beyond the "run" position to a spring-loaded "start" position to provide the initial power pulse. This is an undesired requirement unless the snowmobile possesses an electric starter.
Another prior an variation includes a circuit that produces the momentary pulse of power when it is first fed with continuous power from the ignition switch upon the ignition switch being turned to the "run" position.
All of these prior art variations, however, suffer from the additional disadvantage that after the operator-required action is performed to prepare the snowmobile for operation, the snowmobile will eventually cease to be ready to start if the engine is not started within some period of time thereafter. The readying action will then have to be performed once again. This necessitates the inclusion of an indicator, such as a lamp, to communicate when the system is ready for operation. The rider will then have monitor the indicator in addition to possibly being required to perform further positioning of the ignition switch.
A need exists, therefore, for a snowmobile electrical system that is operational whenever the ignition and emergency stop switches are located in their "run" positions, but that will prevent significant battery discharge when these switches are left in the "run" position after the engine has been turned off.